Tailings Disposal Area Research Articles

Uptake of uranium by aquatic plants growing in fresh water ecosystem around uranium mill tailings pond at Jaduguda, India

Concentration of uranium was determined in aquatic plants and substrate (sediment or water) of fresh water ecosystem on and around uranium mill tailings pond at Jaduguda, India. Aquatic plant/substrate concentration ratios (CRs) of uranium were estimated for different sites on and around the uranium mill tailings disposal area. These sites include upstream and downstream side of surface water sources carrying the treated tailings effluent, a small pond inside tailings disposal area and residual water of this area. Three types of plant groups were investigated namely algae (filamentous and non-filamentous), other free floating & water submerged and sediment rooted plants. Wide variability in concentration ratio was observed for different groups of plants studied. The filamentous algae uranium concentration was significantly correlated with that of water (r=0.86, p<0.003). For sediment rooted plants significant correlation was found between uranium concentration in plant and the substrate (r=0.88, p<0.001). Both for other free floating species and sediment rooted plants, uranium concentration was significantly correlated with Mn, Fe, and Ni concentration of plants (p<0.01). Filamentous algae, Jussiaea and Pistia owing to their high bioproductivity, biomass, uranium accumulation and concentration ratio can be useful for prospecting phytoremediation of stream carrying treated or untreated uranium mill tailings effluent.

Influence of disposal configurations on hydrogeological behaviour of sulphidic paste tailings: A field experimental study

Surface paste disposal (SPD) is a new alternative employed by the mining industry for storage of mine tailings at the surface. In comparison with the conventional slurry tailings disposal, SPD could offer operational and environmental advantages, such as a better water management, no need for complex retaining dams, a reduced footprint of the tailings disposal area, and the possibility to use progressive reclamation. This paper describes a field investigation through a large-scale experimental cell to assess an SPD application for sulphidic mine tailings. The work addresses the effect of two disposal configurations (i.e., partially cemented and un-cemented) on their hydrogeological behaviour when submitted to actual climatic conditions, focusing mainly on the implementation challenges as well as on the first results obtained. Tailings were deposited in thin layers (10 layers of 10cm each one) into two experimental cells (D×L×H=8m×15m×2m). Cement was added locally (2wt.% of Portland cement) in the first layer of the cell (CC) to study its effect; the second cell (UC) is cement free. The evolution of volumetric water content Ѳ, suction ψ, oxygen consumption and cracks for each cell was monitored during and after deposition. Results show that the CC provides slightly higher Ѳ and smaller ψ values than the UC, most likely due to its geological properties dictated by the bottom cemented layer.

Electrical and Seismic Tomography Used to Image the Structure of a Tailings Pond at the Abandoned Kettara Mine, Morocco

The Kettara site (Morocco) is an abandoned pyrrhotite ore mine in a semi-arid environment. The site contains more than 3 million tons of mine waste that were deposited on the surface without concern for environmental consequences. Tailings were stockpiled in a pond, in a dyke, and in piles over an area of approximately 16 ha and have generated acid mine drainage (AMD) for more than 29 years. Geophysical methods have been used at the Kettara mine site to determine the nature of the geological substrate of the tailings pond, the internal structure of the mine wastes, and to investigate the pollution zones associated with sulphide waste dumps. Electrical resistivity tomography (ERT) and seismic refraction data were acquired, processed, and interpreted; the results from ERT and seismic refraction were complementary. A topographical survey of the tailings disposal area was also undertaken to estimate the volume of wastes and quantify the AMD process. Two-dimensional inverse models were used to investigate the geophysical data and indicated alteration zones at depth. It was determined that the material could be classified into three categories: tailings, with low resistivity (5–15 Ω m) and low velocity (500–1,800 m/s); altered, black shales, with intermediate resistivity (20–60 Ω m) and velocity (2,000–3,500 m/s), and; materials with high resistivity and velocity (>60 Ω m and >4,000 m/s, respectively), including unaltered shales associated with quartzite seams. The low-resistivity zone generates AMD, which migrates downward through fractures and micro-fractures. The substrate is composed of broken and altered shale, which facilitates AMD infiltration.

Iron-hydroxide, iron-sulfate and hydrous-silica coatings in acid-mine tailings facilities: A comparative study of their trace-element composition

Abstract Surface alteration-layers often coat minerals in acid-mine drainage systems and the characterization of their chemical composition is required to understand the uptake or release of potentially toxic elements. Samples with micrometer-thick rock coatings were collected from bedrock in contact with three acidic tailings ponds and a small lake, all located within the Copper Cliff mine tailings disposal area in Sudbury, Ontario, Canada. Distribution and concentration of trace-metals in the rock coatings were characterized with Laser-Ablation Inductively-Coupled Plasma Mass Spectroscopy and Micro X-ray Fluorescence Spectroscopy. The rock coatings are composed of goethite, ferrihydrite, schwertmannite, jarosite and amorphous silica. The latter phase is a product of the non-stoichiometric weathering of the underlying siliceous rock. Layers within the coatings are distinguished on the basis of their atomic Fe:Si ratios: FeO x coatings have Fe:Si > 4:1, Si–FeO x coatings have Fe:Si = 4:1 to 1:1 and SiO x coatings have Si > Fe. Iron-rich coatings (FeO x ) in contact with acidic tailings ponds (pH x in contact with lake water at near neutral pH have similar trace-metal concentrations than Si–FeO x and SiO x , most likely the result of higher adsorption rates of metals at near neutral pH conditions. High trace-metal concentrations in Si–FeO x and SiO x are explained by the presence of jarosite-group minerals, which formed within Si-rich alteration layers through mixing of leached alkaline cations and trace elements from the underlying rock and Fe 3+ -sulfate solutions from the pond. Calculated enrichment factors for trace metals and metalloids in the coatings (relative to the pond) indicate that the mobility for Pb, As, Cr and Cu in the upper part of tailings ponds is commonly lower than the mobility for Zn, Mn, Co and Ni. The environmental significance of these findings is discussed in terms of the attenuation of trace metals in the coatings and the widespread occurrences of silica gels and jarosite-group minerals.

Life cycle assessment of mine tailings management in Canada

The effective management of mine tailings involves the control of several environmental impacts and legal requirements. Six tailings site management and closure scenarios were developed for a copper zinc underground mine located in Quebec (Canada) and compared using life cycle assessment (LCA). Two options are considered for the mine operation: tailings can be sent to the tailings disposal area where they are submerged or they can be partly used for backfilling. For each of these two operation options, three alternatives are presented for mine closure: (a) submerged tailings, (b) partial desulphurization with a cover of desulphurized material and (c) a cover with capillary barrier effects (CCBE) made of natural soils followed by revegetation. The goals of the study were to draw the inventory of these management scenarios from the development to the post-closure phase, to assess and compare their environmental impacts and to determine the importance of the land-use impact category. The potential impacts for each scenario were evaluated using the IMPACT 2002+ LCIA method. The results of the performed LCA indicate that for mine development and operation, scenarios where tailings are partly used as backfill for underground stopes appear to lead to larger impacts in 11 of the 14 midpoint categories since the backfill plant operation consumes a greater amount of material and energy. For a site closure period of 2 years, the CCBE option creates the greatest impacts, since it requires much more effort than the other techniques. The results for the post-closure phase have been analysed separately since they have a larger uncertainty. They appear to modify the comparative assessment results. The various results presented in the paper show the importance of taking land-use impacts into account.

Characterization of Surface Soils at a Former Uranium Mill

Dawn Mining Company operated a uranium mill in Stevens County, Washington, from 1957 to 1982, to process ore from the Midnite Mine, and from 1992 through 2000, to extract uranium from mine water treatment sludge. The mill was permanently shut down in 2001 when the Dawn Mining Company radioactive materials license was amended to allow direct disposal of water treatment sludge to a tailings disposal area at the mill. The mill building was demolished in 2003. Site soil characterization took place in 2004. Soil cleanup is ongoing. Contaminated soils on the site were characterized using a GPS-based gamma scanning system. A correlation between shielded gamma exposure rate and concentration of Ra in surface soils was developed. Subsurface soils were sampled using backhoe trenches. This system proved efficient and accurate in guiding development of the remedial action planning for the site and subsequent soil cleanup.

The solid-phase controls on the mobility of heavy metals at the Copper Cliff tailings area, Sudbury, Ontario, Canada

The Copper Cliff Tailings Disposal Area, located near Sudbury, Ontario, covers an area of approximately 2200 ha and constitutes more than 10% of the total area of all mine tailings in Canada. The area has been utilized since 1936, receiving sulphide-containing tailings from the Inco Sudbury operations. Field measurements of pore-gas oxygen and carbon dioxide in the vadose zone indicate that sulphide oxidation has progressed to depths of 1.6 m to 1.7 m within the tailings. The oxidation of sulphide minerals within the vadose zone, and the accompanying dissolution of carbonate and aluminosilicate minerals within these tailings releases SO 4, Fe(II) and other metals to the pore water. In the vadose and saturated zones, concentrations of Fe and Ni exceed 10100 mg/l and 2210 mg/l, respectively. These high concentrations of dissolved metals are attenuated by a series of precipitation, coprecipitation and adsorption reactions. The precipitation of secondary sulphate and hydroxide phases also create hardpan layers at or near the oxidation front. Geochemical modelling of the pore-water chemistry suggests that pH-buffering reactions are occurring within the shallow oxidized zones, and that secondary-phase precipitation is occurring at or near the underlying hardpan and transition zones. Mineralogical study of the tailings confirmed the presence of jarosite, gypsum and goethite within the shallow tailings, suggesting that these phases are controlling the dissolved concentrations of Fe, SO 4 and Ca. Extraction experiments conducted on the tailings solids indicate that the constituents contained in the water-soluble fraction of the shallow, weathered tailings are derived from the original pore water and the dissolution of highly soluble phases such as gypsum. The acid-leachable fraction of the weathered tailings accounts for up to 25% of the heavy metals, and the reducible fraction may contain up to 100% of the heavy metals within the shallow, weathered tailings. Based on the pore water profiles and the geochemistry of the tailings solids, a relative mobility scale of Fe=Mn=Ni=Co>Cd Zn>Cr=Pb>Cu can be determined.

Overview of the Syncrude mining operation

Abstract The Syncrude Canada Limited Operation has been producing synthetic crude oil from a surface oilsand deposit since 1978. The Surface Mine currently supplies an average of 300,000 tonnes per day of ore to the Extraction plant utilizing a strip mining method with draglines, bucketwheel reclaimers, and conveyors. Overburden is removed in advance of the production operation by a large fleet of haul trucks and shovels at a rate of 210,000 tonnes a day. The waste product after bitumen recovery by the Extraction Plant is pumped as a slurry to the tailings disposal area. The Syncrude Mining organization has been successful over the past ten years in the start-up and operation of the Mine and Tailings areas, exceeding the aggressive production and unit cost targets on a consistent basis. This performance record has been accomplished by overcoming the complexities inherent in the Operation through the efforts of the operating and technical organizations. Some of the challenges and successes of the Mine and ...

Effects of phosphorus application and mycorrhizal inoculation on white clover (Trifolium repens) growth in andesite tailings from Martha Mine, Waihi

Abstract The effects of mycorrhizal inoculation and level of applied phosphorus (P) on the growth of white clover (Trifolium repens) in tailings material from a gold and silver extraction process which involved cyanide leaching were examined. White clover gave large growth responses to increasing levels of applied P (0 - 180 μg P/g tailings) and very little growth occurred at low levels of applied P (below 45 μg P/g tailings). At medium - high levels of applied P, inoculation with the vesicular arbuscular mycorrhizal fungus Glomus mosseae resulted in significantly increased yields. Inoculation with topsoil from a site adjacent to the proposed tailings disposal area did not increase plant yields in comparison with plants inoculated with sterilised topsoil. However, there were increased yields in response to both topsoil treatments early on in the experiment. The tailings material appeared to have little or no adverse effect on the development of nitrogen-fixing capacity or mycorrhizal roots. The growth of ...

An experimental investigation of a wind-generated suspension of particulate matter from a tailings disposal area

A wind tunnel investigation of the wind erosion of uranium mine-tailings material typical of a northern Ontario site has been carried out. The aim of the study was to measure the effects of various parameters, including mean and turbulent wind characteristics of the boundary layer and surface moisture content, upon the erosion process. The analysis of experimental data has yielded a mathematical model for predicting the net vertical mass fluxes. The results show that the dry vertical flux is proportional to u * 2.3and the wet flux to u * 5.0 Partical size analysis was also carried out.

Rate controlling processes in the release of radium-226 from uranium mill tailings

Uranium mill tailings (a pyritic quartz conglomerate ore) obtained from a Canadian operation were leached according to a modification of the method recommended by I.A.E.A. for the leaching of radioactive ions from solidified wastes. A static leach test procedure was chosen to provide information to permit an assessment of hazard due to release of Ra-226 to the environment. Narrow range size fractions (53 to 75 μm) of both fresh material obtained directly from a tailings line and material weathered for approximately 10 to 15 yr in a tailings basin were leached for up to 70 days. Distilled water and an acidic synthetic effluent (pH 2.5) were chosen as leachants. Two sequential desorption processes were observed, one before and the other after a leaching period of approximately 10 to 15 days. In the later and more significant stage of desorption, the leaching behaviour could be described in terms of a diffusion mechanism. Significantly greater quantities of 226Ra were leached over relatively short leaching periods by the acidic effluent; thus the quality of the effluent and percolating water in a tailings disposal area would markedly affect the leachability of Ra from tailings. It was also found that the quantities of 226Ra leached were significantly influenced by the solid: liquid ratio at low leaching volumes.

Tailings dam constructed on very loose, saturated sandy silt

This paper discusses the design and performance of a tailings dam constructed over very loose, saturated sandy silt foundation soils. A major slide in an iron tailings disposal area in 1948 resulted in liquefied tailings flowing through a valley and depositing up to 6 m of very loose tailings over glacial till. The properties of the saturated tailings foundation soils were critical to the overall dam design. The new dam will eventually reach a height of 30 m.The paper discusses consolidation and strength parameters of the foundation tailings, design considerations including the potential for foundation and stored tailings liquefaction, and the result of monitoring programs during construction of the starter dam which reached a height of about 9 m. During construction the most critical stability conditions developed during placing of the initial 1.2 m lift of pit-run gravel. After foundation pore pressures dissipated additional fill was placed with no further problems. Contrary to experience with other fine grained angular soils having few clay sized particles, the iron tailings foundation soils consolidated significantly under applied load. It was computed that consolidation under the weight of the starter dam would be sufficient to increase the relative density to a value that would remain stable under maximum anticipated earthquake loadings.